21025000099 has 4 divisors (see below), whose sum is σ = 21033525064. Its totient is φ = 21016475136.

The previous prime is 21025000091. The next prime is 21025000109. The reversal of 21025000099 is 99000052012.

It is a semiprime because it is the product of two primes.

It is a 9-Lehmer number, since φ(21025000099) divides (21025000099-1)⁹.

It is a cyclic number.

It is not a de Polignac number, because 21025000099 - 2³ = 21025000091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21025000091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4258782 + ... + 4263715.

It is an arithmetic number, because the mean of its divisors is an integer number (5258381266).

Almost surely, 2^21025000099 is an apocalyptic number.

21025000099 is a deficient number, since it is larger than the sum of its proper divisors (8524965).

21025000099 is an equidigital number, since it uses as much as digits as its factorization.

21025000099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8524964.

The product of its (nonzero) digits is 1620, while the sum is 28.

The spelling of 21025000099 in words is "twenty-one billion, twenty-five million, ninety-nine", and thus it is an aban number and an uban number.